Introduction: Research evidence indicates that maladaptive reorganization of the brain plays a critical role in amplifying pain experiences and pain chronification,however, no clear evidence of change exists in brain wave activity among patients with chronic low back pain (CLBP). The objective of this study was to assess brain wave activity in patients with CLBP, compared to healthy controls. Methods: Twenty-five patients with CLBP and twenty-four healthy controls participated in the study. A quantitative electroencephalography device was used to assess brain wave activity in eyes-open and eyes-closed (EO and EC) conditions. The regional absolute and relative power of brain waves were compared between the groups. Results: Our results showed a significant increase in the absolute power of theta (F=5. 905, P=0. 019), alpha (F=5. 404, P=0. 024) waves in patients with CLBP compared to healthy subjects in both EC and EO conditions. Patients with CLBP showed a reduced delta absolute power in the frontal region (F=5. 852, P=0. 019) and augmented delta absolute power in the central region (F=5. 597, P=0. 022) in the EO condition. An increased delta absolute power was observed in the frontal (F=7. 563 P=0. 008), central (F=10. 430, P=0. 002), and parietal (F=4. 596, P=0. 037) regions in patients with CLBP compared to the healthy subjects in the EC condition. In the EC condition, significant increases in theta relative power (F=4. 680, P=0. 036) in the parietal region were also found in patients with CLBP. Conclusion: The increased absolute power of brain waves in people with CLBP may indicate cortical overactivity and changes in the pain processing mechanisms in these patients.